| Project/Area Number |
63460010
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KATO Shoji Kyoto Univ. Astronomy Dept. Professor, 理学部, 教授 (80011534)
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| Co-Investigator(Kenkyū-buntansha) |
MATUSMOTO Ryoji Chiba Univ. College of Arts & Science Lecturer, 教養学部, 講師 (00209660)
INAGAKI Shogo Kyoto Univ. Astronomy Dept. Instructor, 理学部, 助手 (80115790)
ISHIZAWA Toshiaki Kyoto Univ. Astronomy Dept. Asoc. Prof., 理学部, 助教授 (10025398)
SAITO Mamoru Kyoto Univ. Astronomy Dept. Asoc. Prof., 理学部, 助教授 (90012856)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1989: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1988: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | Relativistic Accretion / Oscillatory Phenomena / Instability / Quasi-Periodic Oscillations(QPO) / 遷音点 / 振動 / エピサイクリック振動数 / コルゲイション波 |
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| Research Abstract |
Roughly speaking, we had two major results. The first is that (1)the innermost part of relativistic accretion disks is pulsationally unstable, when the so-called alpha-parameter of viscosity is larger than a critical value. The second is that(2) one-armed corrugation waves in the innermost part of relativistic accretion disks are low frequency oscillations whose frequencies are comparable with those of quasi-periodic oscillations (QPO's) observed in low mass X-ray binaries.
(1)The innermost part of relativistic accretion disks has the sonic point where the accretion flow becomes supersonic. We found analytically that the sonic point region is pulsationally unstable when viscosity is large. Subsequently this was confirmed by numerical simulations. Numerical simulations show further that the oscillations have long term variations. This modulation period was found to be comparable with that of QPO'S.
(2)As an oscillations mode whose frequency is as low as that of QPO's, we found one-armed corrugation waves. Corrugation waves are wavy oscillations of disks in the direction perpendicular to the disk plane. We found further that under some circumstances there corrugation waves can be trapped in the innermost part of relativistic accretion disks. This will be in favor of explaining QPO'S.
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